The present invention relates generally to the field of medical diagnostic systems, such as imaging systems. More particularly, the invention relates to a technique for digital-to-film radiographic image conversion.
The classic radiographic or xe2x80x9cX-rayxe2x80x9d image is obtained by situating the object to be imaged between an X-ray emitter and an X-ray detector made of photographic film. Emitted X-rays pass through the object to expose the film, with the degree of film exposure at the various points on the film largely being determined by the attenuation of the object along the path of the X-rays.
It is proposed to utilize solid-state digital X-ray detectors, e.g., an array of photodiodes, in place of film detectors. After the X-ray exposure is terminated, the charges generated on the various points of the detector are read and processed to generate a digital image of the object in electronic form, rather than an analog image on photographic film. Digital imaging is advantageous because the image can later be electronically transmitted to other locations, subjected to diagnostic algorithms to determine properties of the object, and so on.
However, digital images present problems when printed for analysis by radiologists. Because the characteristics of the digital detectors are significantly different from those of film, the images look quite different from analog film images, even when printed on transparent film. This is due to the differing exposure response curves of digital and film detectors. As an example, the digital image data generated by a detector may be linearly proportional to the received radiation (or nearly so), whereas film has a non-linear response to radiation. As a result, the contrast in digital images is not as great as that with radiographic film. To avoid error, radiologists analyzing digital images must keep these differences between analog and digital X-ray images prominently in mind when making such analyses. Therefore, there has been a need for a means of xe2x80x9ctranslatingxe2x80x9d digital images into analog-simulative digital images which mimic the results of standard prior filmed images, and which may be printed on transparent film so that they resemble filmed radiographic images. This would allow the use of light boxes and other tools commonly in use for analysis of analog filmed images.
Solutions to the problems described above have not heretofore included significant remote capabilities. In particular, communication networks, such as, the Internet or private networks, have not been used to provide remote services to such medical diagnostic systems. The advantages of remote services, such as, remote monitoring, remote system control, immediate file access from remote locations, remote file storage and archiving, remote resource pooling, remote recording, remote diagnostics, and remote high speed computations have not heretofore been employed to solve the problems discussed above.
Thus, there is a need for a medical diagnostic system which provides for the advantages of remote services and addresses the problems above. In particular, there is a need for conversion or translation of digital images into images which approximate filmed images, communicating such images and image data over a network, and displaying such images.
One embodiment of the invention relates to a method for converting a digital image to an analog-simulative film-like digital image. The method includes (a.) obtaining digital image input values for a number of pixels, each pixel having a digital image input value X, wherein the range of input values for all pixels defines the input dynamic range; (b.) for each pixel, determining an analog-simulative film-like output value   Y  =                    ∑                  i          =          1                M            ⁢                        A          i                ⁢                  X          Pi                      +          B      i      
wherein Ai, pi, and Bi are real numbers, and M is an integer value greater than or equal to 1; and (c.) communicating the analog-simulative film-like digital image or data associated therewith to a remote facility over a network.
Another embodiment of the invention relates to a method for converting a digital image to an analog-simulative film-like digital image. The method includes (a.) obtaining digital image input values from a number of pixels, each pixel having an input value X, wherein the range of input values for all pixels defines the input dynamic range; (b.) for pixels having input values X less than X1 wherein X1 is a value within the input dynamic range, determining for each pixel an analog-simulative film-like output value Y=A1Xp1+B1 wherein A1, p1, and B1 are real numbers and p1 greater than 1; (c.) for pixels having input values X greater than X2 wherein X2 is a value within the input dynamic range and X2xe2x89xa7X1, determining for each pixel an analog-simulative film-like output value Y=A3Xp3+B3 wherein A3, p3, and B3 are real numbers and p3 less than 1; (d.) generating an output image in accordance with the output values of the pixels; and (e.) communicating the output image or image data to a remote facility over a network.
Another embodiment of the invention relates to a method for converting a digital image to an analog-simulative film-like digital image. The method includes (a.) obtaining digital image input values from a number of pixels, each pixel having an input value X ranging between Xmin and Xmax, the range between Xmin and Xmax defining the dynamic range of the input values; (b.) dividing the dynamic range into N intervals, N being an integer number of at least 1; (c.) for each interval, determining for each input value therein an analog-simulative film-like output value   Y  =                    ∑                  i          =          1                M            ⁢                        A          i                ⁢                  X          Pi                      +          B      i      
wherein M is an integer value greater than or equal to 1, X is the input value, Ai, pi, and Bi are real numbers, and pi decreases with each interval after a first interval adjacent Xmin; and (d.) generating an output image in accordance with the output values of the pixels; and (e.) communicating the output image or image data to a remote facility over a network.
Other principle features and advantages of the present invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description, and the appended claims.